Sealing and insulating means for continuous casting starter bars



J ly 6, 1966 s. L. ANDRZEJAK ETAL 3,262,161 SEALING AND INSULATING MEANS FOR CONTINUOUS CASTING STARTER BARS Filed June 27, 1963 INVENTORS SIGMUND L. ANDRZEJAK ROBERT J. KEENE BYMX M ATTORNEY United States Patent 3,262,161 SEALING AND INSULATING MEANS FDR CON- TINUQUS CASTING STARTER BARS Sigmund L. Andrzejalr, Chicago, and Robert J. Keene,

Chicago Heights, IlL, assignors to United States Steel Corporation, a corporation of N eW Jersey Fiied June 27, 1%3, Ser. No. 291,209 5 Claims. (Cl. 22-572) to use a starter bar to close the lower end of the usual open-bottomed tubular mold at the beginning of a cast. The upper end of the starter bar is inserted into the lower end of the casting mold. Molten metal is then poured into the mold, and is retained therein by the starter bar. In order to permit free insertion of the starter bar into the mold, it is made of the same shape as the mold but with a slightly smaller cross-sectional area. This slight difference in size provides a small clearance between the inner wall of the mold and the side wall of the starter bar. It is necessary to provide means for sealing the clearance between the mold wall and the side wall of the starter bar in order to prevent molten metal from entering this clearance, freezing, and thereby impeding the withdrawal of the starter bar and the casting from the mold.

It is also necessary in the continuous casting of metals to protect the top of the starter bar from the heat of molten metal, in order to facilitate subsequent separation of the starter bar from the leading end of the casting. To achieve this, it is necessary to insulate the top surface of the starter bar thermally from the casting.

An object of this invention is to provide novel means for sealing the space between the interior mold wall and the sidewall of the starter :bar.

Another object of this invention is to provide means for insulating the top of the starter bar from molten metal. 7

Still another object of this invention is to provide a single means which simultaneously provides a seal between the mold wall and the starter bar and also insulates the top of the starter bar from molten metal.

These and other objects will be apparent from the detailed description with reference to the accompanying drawings which follows.

In the drawings:

FIG. 1 is a plan view of the mold and starter bar.

FIG. 2 is a section of the lower portion of a continuous-casting mold and the upper portion of a starter bar inserted therein, showing the novel sealing and insulating element of the present invention, as seen in front section, taken along the line 2-2 in FIG. 1.

FIG. 3 is a side sectional view of the mold and starter bar, taken along the line 3-3 in FIG. 1.

Referring now to the drawings, 10 shows the lower portion of a mold used in the continuous casting of a metal, as for example a ferrous metal or alloy. This mold is shown as having a rectangular shape. While a rectangular shape is desirable for continuous-casting molds, this mold may have any desired shape, as for example polygonal, circular, or oval. A starter bar 12 is inserted into the lower end of mold 110 at the start of casting, as may be seen most clearly in FIGS. 1 and 2. The top surface 14 of starter bar 12 extends only a small distance above the bottom of mold 10. The side wall of starter bar 12 (the term side wall is used herein in the singular to denote the entire side wall surface of the starter bar, whether the bar is of cylindrical shape having a continuous curved side wall or is, as shown herein, a rectangular prism having four distinct side wall faces) is spaced from the inner wall of mold 10 so that there is a small clearance 16 between the mold and the starter bar around the entire perimeter of the latter. As may be seen most clearly in FIG. 3, the mold and the starter bar cross sections have substantially the same shape, but the starter bar is of slightly smaller size than the interior of the mold so as to provide a small clearance. The clearance is preferably as small as possible without having the sides of the starter bar strike the interior mold wall. A clearance of about A3" to about 4" around the entire perimeter of the starter bar is generally suflicient for this purpose.

The entire top surface of starter bar 12 is covered with a flexible heat resistant covering 18, which in the preferred embodiment is a thin asbestos cloth. This cloth is greater in area than either starter bar 12 or the interior of mold 110, so that there is a border portion 20 which extends beyond the perimeter of starter bar 12 and is folded downwardly in clearance 16 between the side wall of the starter bar and the inner wall of the mold, thereby filling said clearance and preventing the entrance of molten metal. The width of this border 20 is not material. A width of about 1 /2" has been found suitable. Thus cloth 18 simultaneously seals the clearance between the mold wall and the starter bar so as to prevent the entrance of molten metal therein, and serves as an insulator for the top of the starter bar. The thickness of the cloth is no greater than the clearance between the mold and the side wall of the starter bar, and may be slightly less.

In order to provide further protection for the top of the starter bar from the heat of the molten metal, and to lessen the impact of molten metal against flexible covering 18, it is generally desirable also to provide a metal chill plate 22 above the asbestos cloth and resting thereon. Chill plate 22 is a thin plate which has a cross section of less than that of the interior wall of mold 10 so that there is a clearance therebetween. The shape and area of chill plate 22 are generally substantially the same as those of the top surface of starter bar 12. However, the chill plate may be slightly smaller and even slighty larger than the top of the starter bar. The thickness of the chill plate may vary within wide limits, but a thickness of about /2" has been found to be quite suitable for prevention of undesirable amounts of heat transmission to start-er bar 12. In order to fill the aforementioned clearance andto provide additional means for preventing the entrance of molten metal int-o the space between the mold wall and the starter bar, a flexible heat resistant packing member 24 is provided between chill plate 22 and the interior wall of mold 10. This packing member extends around the entire perimeter of chill plate 22 and may be of any desired cross section, preferably circular. A preferred material for this packing is asbestos.

Small particles of metal, such as nail heads and metal turnings, are advantageously placed on top of chill plate 22 in order to provide additional protection of starter bar 12 from the heat of molten metal. These particles, being substantially at room temperature prior to the pouring of metal, aid in rapidly cooling and solidifying the lead end of the casting. They are in the form of a thin layer, indicated at 26, with a greater depth around the walls of mold 10 as shown. As seen most clearly in FIGS. 1 and 2, the depth of metal particles increases substantially in the zone immediately adjacent the mold wall. The size of these particles may vary considerably. For example, particles having .a mesh size as fine as V or as coarse as A1," are suitable; in fact, smaller or larger particles .3 may be used if desired, although it is preferredto avoid finely divided particles of powder size.

Upright cylindrical engaging pins 28 having heads 30 are inserted in the upper end of the starter bar and extend from the top thereof, in order to promote connection between the starter bar and the leading end of the casting. These are held in place in starter bar 12 by means of anchor pins 32 which extend through openings in the lower portion of upright pins 28. As shown here, the anchor pins 32 may be of rectangular cross section tapering from one end to the other, and the openings in upright pins 28 are similarly shaped. Both upright pins and anchor pins as described herein are already known. Such structure provides for enhanced interlocking of the solidified lower end of the casting to the starter bar when movement of the latter is initiated, and at the same time permits rapid separation of the casting from the starter bar subsequently. Upright pins 28 in this invention perform an additional function not previously known in the art, and that is to position asbestos cloth and chill plate 22 relative to starter bar 12.

Starter bar 12 is inserted into the lower end of tubular mold 10 before the start of a casting. Mold 10 may be a conventional continuous casting mold of uniform cross section and open at both ends. When the lower end of mold 10 has been plugged by means of starter bar 12, including the insulating cloth 20, chill plate 22 and metal particles 26, when used, molten metal is poured into mold 10 until the level of said metal reaches a predetermined height at or near the top of the mold. The outer skin of metal in mold 10 and the lower portion adjacent starter bar 12 then solidify. When the predetermined level has been reached, starter bar 12 is then lowered by conventional means, such as pinch rolls. The lead end of the casting, which has solidified in engagement with pins 28, is brought downwardly at the same speed. Entrance of molten metal into the clearance between the inside wall of mold 10 and the side wall of starter bar 12 is prevented by the apparatus of the .present invention.

While we have described this invention with reference to a specific embodiment for the purpose of illustration, the scope of the invention is to be measured only by the scope and spirit of the appended claims.

We claim:

1. In combination with a tubular mold for continuous casting of metals, a starter bar adapted to be inserted into and a slightly smaller size, whereby there is a small clearance between said starter bar and the interior wall of the mold, and a flexible heat-resistant sealing member secured to the top surface of said starter bar and completely covering said top surface, said sealing member having a border portion extending beyond the perimeter of said top surface and turned downwardly into said clearance between said mold and said starter bar, whereby entrance of molten metal into said clearance is prevented.

2. In combination with a tubular mold for continuous casting of metals, a starter bar adapted to be inserted into the lower portion of said mold, said starter bar being of substantially the same cross-sectional shape as said mold and a slightly smaller size, whereby there is a small clearance between said starter bar and the interior wall of the mold, and a flexible heat-resistant sealing member secured to the top surface of said starter bar and completely covering said top surface, pins extending from the top of said starter bar through said member, said sealing member having a border portion extending beyond the perimeter of said top surface and disposed in said clearance between said mold and said starter bar.

3. Apparatus according to claim 2 wherein said starter bar has a thin metal plate having the same shape as said mold and a slightly smaller size than said mold disposed above said flexible sealing member.

4. Apparatus according to claim 3 wherein said starter bar has a heat-resistant packing in the space between said metal plate and said mold.

5. Apparatus according to claim 4 characterized by small pieces of metal resting loosely on said metal plate.

' References Cited by the Examiner UNITED STATES PATENTS 3/ 1954 Great Britain.

7/ 1957 Switzerland.

J. SPENCER OVERHOLSER, Primary Examiner. 

1. IN COMBINATION WITH A TUBULAR MOLD FOR CONTINUOUS CASTING OF METALS, A STARTER BAR ADAPTED TO BE INSERTED INTO THE LOWER PORTION OF SAID MOLD, SAID STARTER BAR BEING OF SUBSTANTIALLY THE SAME CROSS-SECTIONAL SHAPE AS SAID MOLD AND A SLIGHTLY SMALLER SIZE, WHEREBY THERE IS A SMALL CLEARANCE BETWEEN SAID STARTER BAR AND THE INTERIOR WALL OF THE MOLD, AND A FLEXIBLE HEAT-RESISTANT SEALING MEMBER SECURED TO THE TOP SURFACE OF SAID STARTER BAR AND COMPLETELY COVERING SAID TOP SURFACE, SAID SEALING MEMBER HAVING A BORDER PORTION EXTENDING BEYOND THE PERIMETER OF SAID TOP SURFACE AND TURNED DOWNWARDLY INTO SAID CLEARANCE BETWEEN SAID MOLD AND SAID STARTER BAR, WHEREBY ENTRANCE OF MOLTEN METAL INTO SAID CLEARANCE IS PREVENTED. 